The bearing device for a wheel has evolved from a structure called first generation in which double-row roller bearings are independently used to second generation in which a vehicle body attachment flange is integrally provided in an outer member. Further, third generation in which one inner rolling surface of the double-row roller bearings is integrally formed with an outer circumference of a hub wheel integrally having a wheel attachment flange has been developed. Further, fourth generation in which a constant velocity universal joint is integrated with the hub wheel and another inner rolling surface of the double-row roller bearings is integrally formed with an outer circumference of an outer joint member constituting the constant velocity universal joint has been developed.
For example, the bearing device for a wheel called third generation is described in Patent Document 1. The bearing device for a wheel called third generation includes, as illustrated in FIG. 37, a hub wheel 152 having a flange 151 extending in a radially outer direction, a constant velocity universal joint 154 having an outer joint member 153 fixed to the hub wheel 152, and an outer member 155 arranged on an outer circumferential side of the hub wheel 152.
The constant velocity universal joint 154 includes the outer joint member 153, an inner joint member 158 arranged in a cup-shaped section 157 of the outer joint member 153, a ball 159 arranged between the inner joint member 158 and the outer joint member 153, and a cage 160 that retains the ball 159. A spline portion 161 is formed on an inner peripheral surface of a center hole of the inner joint member 158. An end spline portion of a shaft (not shown) is inserted into this center hole, whereby the spline portion 161 on the inner joint member 158 side and the spline portion on the shaft side are engaged.
Further, the hub wheel 152 includes a cylindrical section 163 and the flange 151. A short-cylindrical pilot section 165, on which a wheel and a brake rotor (not shown) are mounted, is protrudingly provided on an outer end surface 164 (end surface on an outboard side) of the flange 151. Note that, the pilot section 165 includes a large-diameter first portion 165a and a small-diameter second portion 165b. The wheel is externally fitted onto the first portion 165a, and the brake rotor is externally fitted onto the second portion 165b. 
Then, a notch section 166 is provided in an outer peripheral surface at an end portion on the cup-shaped section 157 side of the cylindrical section 163. An inner race 167 is fitted in the notch section 166. A first inner raceway surface 168 is provided near a flange on an outer peripheral surface of the cylindrical section 163 of the hub wheel 152. A second inner raceway surface 169 is provided on an outer peripheral surface of the inner race 167. Further, a bolt inserting hole 162 is provided in the flange 151 of the hub wheel 152. A hub bolt for fixing the wheel and the brake rotor to the flange 151 is inserted into the bolt inserting hole 162.
In the outer member 155, double-row outer raceway surfaces 170 and 121 are provided on an inner circumference thereof, and a flange (vehicle body attachment flange) 182 is provided on an outer circumference thereof. A first outer raceway surface 170 of the outer member 155 and the first inner raceway surface 168 of the hub wheel 152 are opposed to each other. A second outer raceway surface 171 of the outer member 155 and the raceway surface 169 of the inner race 167 are opposed to each other. Rolling elements 172 are interposed between those inner and outer raceway surfaces. In other words, an inner member of the roller bearing is constituted by the inner race 167 and a part of an outer surface of the hub wheel 152.
A shaft section 173 of the outer joint member 153 is inserted into the cylindrical section 163 of the hub wheel 152. In the shaft section 173, a screw section 174 is formed at an end portion of a reverse cup-shaped section thereof. A spline portion 175 is formed between the screw section 174 and the cup-shaped section 157. Further, a spline portion 176 is formed in an inner peripheral surface (inner surface) of the cylindrical section 163 of the hub wheel 152. When the shaft section 173 is inserted into the cylindrical section 163 of the hub wheel 152, the spline portion 175 on the shaft section 173 side and the spline portion 176 on the hub wheel 152 side are engaged.
A nut member 177 is screwed into the screw section 174 of the shaft section 173 projecting from the cylindrical section 163. The hub wheel 152 and the outer joint member 153 are connected. In this case, an inner end surface (back surface) 178 of the nut member 177 and an outer end surface 179 of the cylindrical section 163 are brought into contact with each other and an end surface 180 on the shaft section side of the cup-shaped section 157 and an outer end surface 181 of the inner race 167 are brought into contact with each other. In other words, when the nut member 177 is tightened, the hub wheel 152 is sandwiched by the nut member 177 and the cup-shaped section 157 through the inner race 167.
Patent Document 1: JP 2004-340311 A